In the PTR before Patch 3.2.0 was released, the criteria read as follows.

Defeat the Black Knight in 10 minutes while wearing all blue items, before 3 Volcanos erupt, while everyone in the group has at least 1 stack of Spurting Blood and there are no shamans or paladins in the party but before you spend at least 1000 gold in repairs wiping to the Black Knight.